GILROY, Calif. — Calmer, cooler weather helped firefighters get a handle Sunday on a destructive wildfire in the Santa Cruz Mountains that has brought a fierce start to the state's fire season.

Easing winds and lower temperatures helped keep the blaze from spreading after flames charred nearly 6 square miles and destroyed at least 20 homes since Thursday, according to the California Department of Forestry and Fire Prevention.

"It's really not moving at all," said David Coursey, a department spokesman.

The fire was about 50 percent contained Sunday morning and was expected to be fully surrounded by early next week, fire officials said. The blaze still threatened 550 homes and 20 other buildings.

Hundreds of residents remain under evacuation following the outbreak of the fire in the mountainous region about 15 miles south of San Jose. Five firefighters have suffered minor injuries.

Nearly 2,900 personnel worked to cut fire lines through centuries-old redwood forests as a swarm of helicopters and air tankers doused flames from the sky.

State of emergencyGov. Arnold Schwarzenegger has declared a state of emergency for Santa Cruz and Santa Clara counties to allow access to state funds. The firefighting effort has cost $6.1 million so far, Coursey said.

Smoke from the wildfire has left a haze over the San Francisco Bay area that was expected to linger through the three-day Memorial Day weekend.

About 2,000 residents have been asked or ordered to evacuate their homes since the fire started Thursday.

Some evacuees were being let in on an hour-by-hour basis to survey the damage, and plans were being put in place to allow many to return to their homes soon, officials said.

Investigators are still probing the cause of the fire, which broke out just as the state's unofficial fire season got under way in mid-May. The blaze erupted following the state's driest two-month period on record.